A plant-based COVID vaccine is going into arms

Canadian biopharm company Medicago and pharmaceutical giant GlaxoSmithKline (GSK) are moving their plant-based COVID-19 vaccine into phase 3 trials.

“We are pleased to take the significant step of initiating the Phase 3 clinical trial at sites around the world,” Medicago CEO and president Takashi Nagao said in a press release.

 “This brings us one step closer to delivering an important new COVID-19 vaccine and contributing to the global fight against the pandemic along with our partner GSK.”

Initial testing of the vaccine began late last fall, after it was found to provoke the creation of antibodies that neutralize the virus. 

In February, the vaccine was granted FDA Fast Track designation — which allows for sped-up development and review of medicines aimed at medical emergencies.

Medicago’s COVID-19 vaccine uses both a different form of production and a different form of target (known as an antigen) to goose the immune system.

Pfizer and Moderna’s mRNA vaccines use the genetic code of the coronavirus’s spike protein as an antigen, while Sinovac’s vaccine uses killed or inactivated virus.

The Medicago vaccine uses “Coronavirus-Like-Particles” (CoVLPs) for its antigen. As their name suggests, these particles mimic viruses but lack any of the genetic material. The immune system should respond to them like viruses, even though they can’t replicate or cause an infection.

These imitation viruses are created in the leaves of N. benthamiana, tobacco’s Aussie relative, “where it reproduces as the plant grows, making more antigens that can be harvested from the plants,” as our own Kristin Houser explained about another tobacco-based COVID-19 vaccine.

Because particles that just float around without doing anything don’t look very much like an infection, the immune system often doesn’t respond very strongly to them, so the vaccine is then paired up with an adjuvant — a compound meant to increase the immune reaction — from GSK. 

Like most other COVID-19 vaccines, the Medicago/GSK vaccine is administered in two doses.

The phase 3 trial will test the vaccine against a placebo, enrolling up to 30,000 people, beginning with healthy adults between 18 and 65 before moving on to 65+ and people with comorbidities. 

Starting in Canada and the U.S., the study is aiming to be held in eight more countries, pending regulatory approval, the release states.

While it seems like a niche field, Medicago’s not alone in the plant-based coronavirus vaccine game, as British American Tobacco and iBio are also working on candidates.

Further along still are plant-based vaccines for flu, with Medicago’s performing well in large clinical trials.

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